This invention relates to inertial latching mechanisms particularly adapted for preventing forward folding of a motor vehicle seat back when the vehicle is exposed to a deceleration force above a predetermined level.
As a safety feature, motor vehicle seat backs which have forward folding or "dumping" capability are provided with some means to prevent forward folding of the seat back when the vehicle is exposed to significant deceleration loads which occur, for example, in vehicle frontal impact conditions. Front vehicle seats in two-door vehicles generally can be folded forward to enable access to the rear compartment area. Similarly, station wagon style vehicles often have a second seat which can be folded forward to provide a load carrying area. Manually released latching mechanisms have been used for such folding seats which require the user to actuate the mechanism before the seat back can be dumped forward. Although these devices perform satisfactorily, they are inconvenient to use. As a means of enhancing operator convenience, motor vehicle manufacturers frequently provide inertia sensitive latching mechanisms which normally enable the seat back to be freely dumped forward, but sense vehicle deceleration to lock up and prevent such dumping in vehicle impact conditions.
The inertia latch assemblies of the present invention have widespread potential application but are particularly suited for station wagons or similar vehicles to restrict forward folding of the seat back of a second passenger seat. When the seat back of the second seat of a station wagon is folded forward, it is desirable to provide a flat and unobstructed load floor. Therefore, the latching mechanism for the seat back should not present obtrusive projections in the load floor area. The latch assemblies according to this invention provide inertia sensitive operation, are simple in terms of their design, operation and assembly, and are fully enclosed within the seat back structure for protection.
In accordance with this invention, inertial latch assemblies are provided which are mounted within a seat back foam pad. A latching hook coupled to a seat support structure engages the inertial latch pendulum through an aperture in the seat back. In order to enhance the reliability of operation of the device, the pendulum forms a cam surface which rotates the pendulum into an engaging position upon contact with the latch hook when the seat back is in its normal upright position. Forward movement of the seat back causes the pendulum to rotate out of engagement with the hook, unless the vehicle is exposed to deceleration loads above a predetermined level, in which case the pendulum remains in engagement with the latching hook.
In accordance with a second embodiment of the invention, an inertial latch assembly is provided which further incorporates a retaining clip which maintains the pendulum in an engaging position after the vehicle deceleration loads are relieved. The clip prevents disengagement of the pendulum in multiple vehicle impact situations in which the vehicle may experience repeated deceleration loads over a short duration.
Additional benefits and advantages of the present invention will become apparent to those skilled in the art to which this invention relates from the subsequent description of the preferred embodiments and the appended claims, taken in conjunction with the accompanying drawings.